1. Technical Field
The present disclosure relates to a vehicle control device and a vehicle control method.
2. Related Art
There is a conventionally known technology of, for example, detecting a preceding vehicle ahead of a vehicle to which the technology is applied (which will be referred to as subject vehicle), and activating an alarm and automatically controlling the brake to prevent the subject vehicle from bumping against or colliding with the detected preceding vehicle. For example, Japanese Unexamined Patent Application Publication No. S63-78300 discloses a collision preventing device that raises an alarm for a driver on the basis of the velocity of the subject vehicle, the inter-vehicle distance to a preceding vehicle, and the preceding vehicle's brake lights that are switched on and off.
The technology, however, causes the sudden deceleration of the subject vehicle due to a braking operation by the alarmed driver or automatic brake control. The sudden deceleration of the vehicle converts the kinetic energy of the vehicle into thermal energy, and at least part of the thermal energy is lost. It is thus problematic that the sudden deceleration of the vehicle would decrease the energy consumption efficiency of the vehicle as compared with slow deceleration. In addition, a driver is expected to accelerate the vehicle to keep on driving after decelerating the vehicle, but in general, the torque transmission efficiency becomes lower when the vehicle is accelerated than when the vehicle is maintained at constant velocity. Consequently, the energy consumption efficiency of the vehicle may decrease.